Intriguing news on the airship beat today, as it is reported that a mysterious, well-nigh miraculous new technology – one which could potentially lead to the appearance of enormous aerial vessels fit to dwarf even the zeppelin leviathans of the 1930s – is to get flight trials within two years.
Concept for a heavy-lift military …

Has anyone looked at a mix of gases ..

Zeppelin thought of that

The original design for the Hindenberg would have used hydrogen 'anti ballast' held in relatively small gas bags buried within the much larger helium-filled lifting bags. As the ship burned fuel, hydrogen would have been vented, reducing the lift.

For all sorts of reasons, mostly to do with the cost of securing helium, the design was abandoned for a single set of gas bags.

Aren't saying the same thing?

Or a mix of H and He

If you were to blend cheaper hydrogen with the helium it would it be inflammable? presumably at a certain percentage yes, below that no. A bit like how the 80% nitrogen in the air mitigates the propensity of the oxygen component to react with flammable substances.

If a H/He mix was "safe" with a high H content the overall cost would reduce and venting gas more affordable (and indeed, the capital cost of filling the airship initially would be less).

Just get over Hindenburg and use hydrogen

True

It's not such a bad suggestion. There are other dangerous substances used in transportation that are just handled more safely; airline fuel and petrol for starters. Although Hydrogen is nice and explode-able, if it's held securely and all relevant safety precautions are met it becomes more viable.

Despite the Hindenberg being the last of 22 hydrogen-lift airships to catch fire, they all seemed to have the same basic construction and tech. Think: how many tests did NASA do before actually putting someone at the top of a giant firecracker that can explode at any moment? If the best idea is only marred by one fundamental hurdle then we only need scale that particular hurdle. Make Hydrogen safe and we have an almost perfect solution to heavy lift logistics.

All about context

On the face of it, sound comments all-round.

However, the purpose of this vessel is for military use. Military vehicles in dangerous situations don't tend to carry with them enough fuel to cause enough concern past their own safety. This thing is for transporting large numbers of lives outside of safe airstrips, the very last thing it needs is to be vulnerable to internal detonation.

Gas use.

There is no need to use Hydrogen from an economic or safety point of view. Once you fill a modern hybrid air vehicle with Helium it uses very little Helium due to the fact that modern envelope materials have increadibly low leakage rates and that the internal pressure differential is minimal, so even a few dozen bullet holes would not make much of a difference (Not that anyone flies so low). The days of using goldbeaters skin and rocket fuel for paint ended ages ago.

The cost of jet fuel is the real issue and the ability of a modern hybrid to do long range point to point cargo, passenger or surveillance operations for one third of the total fuel is one big factor behind the LEMV program in particular.

Hydrogen use.

Helium is the only approved lifting gas and no serious insurance company will go near a project using explosive Hydrogen. Just remember the nuke reactors in Japan venting Hydrogen had a slight explosion or two recently.

Helium is very abundant as a by product of natural gas liquifaction and there are vast reserves in the gas fields of Qatar, Eastern Siberia, Algeria and new yet untapped reserves in Australia.

If you want to read more on the subject, there is a Helium page on my comedy web site 3w airship.me

cost of jet fuel related to cross-section?

But then a hydrogen based blimp will have a considerable advantage in weight-to-volume lift ratios of the gas bags, resulting in a smaller cross section, and less drag, so greater range (or much larger payload capacity). Am I missing something here?

That said, the other problems with hydrogen (often glossed over by armchair designers) coupled with the problems in getting any such design ok'd by either the FAA (or most of their international counterparts) or any underwriter makes hydrogen as a lifting gas a lost cause, leaving such questions academic anyway.

"Abundance" is a relative term.

Helium may be "abundant" in and around the earth, but CAPTIVE helium, in its pure molecular form, is difficult to isolate. Don't confuse the two.

The US used to have a vast reserve, created by government, that the government has since decided to sell off. The dumping of that reserve has ruined the market for helium in the US, which means that we aren't producing it anymore in sufficient quantities.

We could, but we aren't. Are you suggesting that we buy helium from Qatar or Australia? Before that is necessary, we could start producing it again ourselves. But right now, our reserves are low. Granted, government created the reserve in the first place, but government is currently spending that reserve in a way that destroys the market.

Fixed volume?

COSH

COSH is a longer term research only project. The real answer is the use of a hybrid air vehicle design and the associated far heavier take off static weight that means you do not need to carry heavy compressors or very difficult to certify composite pressure tanks that need to be both fire and bullet proof.

Adding Air...

Airship Industries had a method whereby they added outside air into a sealed sock inside the main envelope. This is a net gain in weight because it is adding something that wasn't there before. I suppose that recovering water from the exhaust is adding external weight, but it doesn't half seem like a long way to go about it, for something that can be done with a small pump.

Blimps/dirigibles in a combat zone

Re: Blimps/dirigibles in a combat zone

Blimps are currently being used in Afghanistan, at a low enough altitude that occasional lucky pot-shots with a rifle will hit. We fixed it with gaffer tape and more helium. The body was resilient enough that multiple holes weren't a show-stopper, although we had to keep a steady supply of helium coming in.

If someone actually used a missile then all bets are off, but I'm sure these would be escorted by helicopter/jet CAS in a combat zone.

AA fire.

Not a real risk factor as the Taliban et al don't have any missiles that can reach 20,000 ft, which is the operating altitude of the LEMV and the two diesels won't give an IR lock on unless you stand next to one with your SAM 7 etc. Luckily they can't even shoot down low flying Helicopters these days.

Thunderbird are go?

Wasteful use of Helium

He is a very rare gas - since it is only produced as a byproduct of radioactive/nuclear processes. As such, it's probably THE least renewable substances we know of - and far too useful and valuable to waste of merely ferrying american soldiers around.

Usage and Wastage

Lewis is sadly getting our hopes up when he has already written that he knows better:

* http://www.theregister.co.uk/2010/02/05/helium_dome_forever/

There may be plenty of my favourite M&S sandwhiches being stocked each day, but if I never bother to grab them in time they are for all practical reasons as rare as scotch-mist. (And yes I was late, and yes it was egg and cress, and yes everyone in the office regretted my choice).

Total rubbish.

You have got Helium 3 mixed up with normal Helium. There is plenty of Helium available as a by product of natural gas liquifaction from the vast gas fields of Qatar, Eastern Siberia, Algeria and new finds in Australia. You will run out of oil well before you run out of Helium, although solar panels will be so efficient by then, that the hybrid air vehicles with their flatter lifting bodies will all be solar assisted diesel electric designs rather than the present high tech German diesel engines.

See the Helium page of my Gasbags site 3w airship.me for more info on Helium supply.

Helium.

If you want to know more about how cheap Helium is see the Helium page of my Gasbags comedy site: www.hybridblimp.net and click on the last press link about all the Helium in Eastern Siberia, Qatar and Algeria.

Bullet holes.

They only have a long term effect in terms of topping up the gas fill, as the internal pressure differential is so low and the envelope volume so high that you can fly even with a few unrepaired holes.

Hindenburg and aircraft dope

Hi,

The Hindenburg fire started from a static discharge that ignited the extremely inflammable paint job that had been used on the fabric skin. This was silver coloured aircraft dope, consisting of a mixture of aluminium powder and cellulose acetate.

The hydrogen only caught fire as the fabric skin burnt away and the flames reached the H2 gas cells. If you watch the film of the fire you can see that the hydrogen just burn off, there was never any explosion.

Another useless fact about hydrogen, some years ago I read that when you got "air" in your house central heating radiators, it was probably hydrogen evolved from the reaction of acidic water and the copper pipes and steel radiators. At the time I had "air" in my home rads, so in the spirit of scientific investigation I found the bleed key, opened the valve on one of the "air" locked rads and applied a lit match to the gas rushing out, I was amazed to see a foot long blue flame roar out of the bleed valve for a minute or so. Looking back on it I was perhaps lucky that the rad was full of H2 and not a explosive mixture of H2 and air, so I did not blow the rad apart, and possibly the wall as well!

@oldcodger

I thought it was thermite

I recall that the outside of the Hindenberg was first painted with iron oxide paint - as was everything in those days, and then they painted it silver to reduce the solar load, or to make it pretty, whatever.

As any fule no, iron oxide and aluminium powder not the best choice of fireproof coating.

Bullet holes...

Don't do a hell of a lot. It took incendiaries to start making a difference to the Zeppelins bombing london in WW1

Hydrogen is relatively safe, but it's a bitch to work with in terms of its tendency to make things brittle. Even standard rubber toy balloons go funny after 3-4 days of having hydrogen in them (Many countries use it for balloon gas because helium is "too expensive")

I wondered about using Compressors ~25 years ago as a way of neutralising bouyancy. Guess I should have patented the idea. :)

Forget about the Hindenburg, that was an aluminum fire. You should be more worried about R101-syle scenarios (The USA lost both its US Navy lifters in similar incidents). Airships don't fare well in microbursts.

HAV's in convective activity.

Hi All,

Modern weather radar installed in the new hybrid air vehicles will do a lot to negate any risks from downbursts when combined with ground and satellite based weather radar systems for the bigger picture. The Germans never lost a big Zeppelin making numerous croosings of the ITCZ (Inter tropical convergence zone) which having crossed it heading for Brazil in a yacht and flying around Trinidad, is one very bad place for severe thunderstorms.

The modern hybrid air vehicles like the LEMV (HAV 304) are much more powerful with their high tech German diesels and when combined with the lifting body shape they can start a sudden climb or descent in a much more decisive way than an old Zeppelin. They do not fly like an airship as they have both more power available and a flying wing shape that will enable them to deal very effectively with up or down draughts, although they are much safer in severe turbulence because you can not loose control of one, as they have positive stability factors from pendulous stability, so can't be tipped over in flight. If an active tropical storms or tornadoes are avoided they are very safe and the long endurance of such diesel engined HAV's means they will have the reserves at destination to hold clear for days if required. Not quite the situation of the Air France Airbus they are fishing up at present in terms of ultimate safety.

Superheating the helium at take-off

I read this, as in heating the gases in an airship for rapid ascent, mid-battle, in one of the Oswald Bastable books by Michael Moorcock. I'm not saying that MM invented it, although as a fantasy writer that is his job, it might be something that was theorised or even practised years before.

Can anyone enlighten me please as to whether or not this was the origin of this idea?

'Well-nigh miraculous new technology'

The obvious answer

to the problem of excess buoyancy as fuel is burnt is to use a small nuclear power plant instead. I for one am amazed that Lewis, of all people, did not mention what appears to be the ideal technology for giant airship propulsion.

According to Wikipedia: "A small reactor was used to supply power (1.5 MWe) and heating to McMurdo Station, a US Antarctic base, for ten years to 1972, testing the feasibility of such air-portable units for remote locations."

Clearly you would need a large airship just to carry the reactor but, with efficient modern motors and 1.5 MWe to play with, there should be plenty of juice left over to power something several times larger!

COSH revolution

Neat idea which keeps in mind pespective.

It seems when people have looked at the compressor idea they imagined *huge* compression ratios (100s of atm in the tank). This fellow has worked out its about changing the *average* density of the airship itself. Pumps the He into some double or triple strength gas bags, leave air in the rest and voila, down she goes.

Neat. Subtle and a good use of the greatly increased room temperature strength of various fibers.

On the topic of bullets. An old school friend told me about a demonstration they gave at his officer cadet course.

The fired some machine gun rounds (9mm) at a water soaked blanket hanging on a clothes line.

The bullets did not pass through.

The combination of heavy load (the wet blanket is 100x of times heavier than any bullet) which was free to fall backwards decelerated the bullet enough to retain it in the layers of blanket.

The builders of the Atlas launch vehicles (not the current design) used to demonstrate that hitting it *hard* with large mallet had no effect on it despite it only being kept stable by internal air pressure.

I think this sort of airship will use a tight woven Kevlar for its skin so as long as the air pressure is not too high normal rounds won't work (not after they have decelerated by being fired a km straight up. Incendiary *might* ignite the Kevlar and all bets are off with armor piercing but this is a *very* big structure. It would *sink*, not crass like an aircraft.

I wish them luck with the prototype. Personally I would have tapped the gas cells in the Zeppelin and used *them* for fuel. But what do I know.

100s of Atmospheres...

Yeah you could do that, but that would be one heck of a pile of work. I'd use high volume compressor plumbed into the gas bags along the length of the ship so that one could more accurately control the air-ballast. Use a composite tank that runs the length of the ship (or series of them plumbed together). Why composite tanks? Well they are good for extremely high pressures (doesn't mean you have to use them that way), making them nice and safe when used at high altitude in an unpressurised environment (why have the tanks in the pressure-vessel?).